With El Niño bearing down, federal emergency officials on Wednesday issued their strongest warnings yet, urging Californians to prepare for the predicted onslaught of storms by taking immediate steps that could save lives and property.

“It is critical that citizens take the risk seriously,” said Bob Fenton of the Federal Emergency Management Agency, who led an emergency response drill with regional agencies in Sacramento on Wednesday.

If this El Niño mimics the winters of 1982-83 and 1997-98, as expected, Bay Area counties face a trifecta of flood risk: seasonally high “king tides,” storm-induced surges near beaches, and rising rivers along flood plains, experts said. Already, sea levels are higher than normal, due to El Niño’s warm ocean temperatures.

Residents in flood-prone California, especially, should do the following: research their risks and reduce them before the rain starts, create a family emergency plan and buy flood insurance.

“People don’t plan to fail — they fail to plan,” said Todd Morris, National Oceanic and Atmospheric Administration’s Regional Coordinator for Weather Services. “Nobody is intentionally reckless with their lives or their family’s lives. Everybody wants to do the right thing. … But there is potential for disaster.”

While officials are ready to assist in emergencies, they prodded residents to reduce risk now by taking responsibility for themselves, their family and their community.

“If you hear a warning to evacuate, act accordingly,” Fenton said. “People often want to ‘wait and see’ — but, please, don’t wait. Everything can be replaced, but your life can’t.”

Homes on the Santa Cruz, San Mateo and Monterey coasts are at high risk due to winds and so-called “storm tides,” the combination of ocean storm surge and the astronomical tide, said Morris. For example, a 15-foot storm surge on top of a 2-foot high tide can send waves cascading onto property 17 feet beyond usual levels.

Homes in communities that ring the Bay may be at risk if there is a “king tide,” said Morris. King tides are anticipated for late December as well as late January. These low-lying areas also face flooding due to swollen rivers.

If all of these scenarios converge, “there’s a domino effect,” said Morris.

Landslides also are a threat. More than $22 million was doled out by FEMA to California victims of landslides during the 1997-98 El Niño, including about $8 million for homes in Pacifica, La Honda and Loma Mar, Daly City, Aptos, Boulder Creek and parts of Sonoma County.

The severity of El Niño’s impact will depend on the volume of rainfall and the duration of rains, said Morris. The perfect storm delivers “a gentle light rain that continues for several days, soaking in,” he said.

Many Californians have already taken heed of warnings, the experts noted. About 7,100 new flood insurance policies have been purchased in the last month.

El Niño — named years ago by Peruvian fishermen for the Christ child because it typically starts around Christmas — is already creating a crazy quilt of weather around the nation.

While the West Coast hasn’t yet felt El Niño, caused by abnormal warming of the surface waters of the equatorial eastern Pacific Ocean, other parts of the United States are breaking weather records, according to the National Weather Service.

This month, Texas, Oklahoma, Arkansas and portions of South Florida received five to eight inches more rain than normal. Detroit experienced its sixth-warmest November since 1874. October gave Bismark, North Dakota, a rare 90-degree day and one of the latest snowfalls on record; the state will continue to see warmer than normal temperatures throughout the winter, meteorologists predict.

In California, forecasters predict that El Niño-related conditions will start in January and last through March.

“We are looking at the potential for one of the strongest El Niños in recorded history,” said Morris.

In some areas, such as Lake and Calaveras counties, mountains are black and bare from fires, with mud ready to tumble in massive landslides. Flash flooding is another risk in these communities.

Experts are also worried about the low-lying Central Valley, where levees and dikes may be unable to hold water from raging rivers. In 1997, flooding inundated nearly 300 square miles of the valley, covering about 26,000 structures, forcing evacuation of 150,000 people and killing eight.

In the Sacramento Valley area, where the large Sacramento and San Joaquin Rivers converge, “rain coming down those rivers has very little area in which to go,” said Fenton, who worries about the ability of the levee system to hold rising waters.

In the southern San Joaquin Valley, four rivers — the Kaweah, Kern, Kings, and Tule Rivers — empty into the old Tulare Lake basin area, which historically floods. The once-rural region is now filled with homes, highways, water treatment facilities, and valuable oil and natural gas infrastructure.

At the Wednesday rehearsal, government officials reviewed procedures, identified at-risk populations and facilities and discussed some of the gaps and shortfalls that remain.

“But this is not just a government solution but a public-private ‘all hands on deck’ solution,” said Fenton.

“We all need to be out in front of this, as it is happening,” he said.

Understand your risks, then reduce them, before rains start. A state-run website called Map My Hazards (http://myhazards.calema.ca.gov) reveals the flooding and landslide hazards that exist near your home and workplace.

Create a family emergency communication plan, if power goes down or roads are inaccessible. The federal “Make A Plan” website (http://www.ready.gov/make-a-plan) provides tips and templates.

Purchase flood insurance, if you’re in a susceptible area. Homeowners insurance policies do not cover flood damage, they said.

Keep special supplies in case power goes down, such as flashlights, a battery-operated radio, extra food and water, and extra batteries, they said.

Clear any debris in yards that could clog the flow of water. And, if a home is prone to flooding, use sandbags.

Lisa M. Krieger is a science writer at The Mercury News, covering research, scientific policy and environmental news from Stanford University, the University of California, NASA-Ames, U.S. Geological Survey and other Bay Area-based research facilities. Lisa also contributes to the Videography team. She graduated from Duke University with a degree in biology. Outside of work, she enjoys photography, backpacking, swimming and bird-watching.